Method of Joining an Outer Sheet and an Inner Sheet, in Particular of an Attachment Part of a Motor Vehicle Body

Abstract

A method provides for joining an outer sheet and an inner sheet, in particular of an attachment part of a motor vehicle body. On the visible sides of an attachment part, a welding or brazing seam is produced between a fold of an outer sheet and an inner sheet. The outer sheet is held in a bed, and the inner sheet is pressed against the fold on an inner side thus forming a joining groove. To ensure that during beam welding or beam grazing the inner sheet is held in position on the fold, it is prevented from moving away without clamping by stops on an outer side. These stops are disposed in a row along the welding or brazing seam and in dependence upon the progress of the joining procedure can be moved individually out of a path of a welding or brazing head.

1 . Method of joining an outer sheet and an inner sheet,
 wherein the outer sheet comprises, at least on a partial section of its circumferential edge, a fold which is directed towards the inner sheet and to which the inner sheet, which is pressed with an inner sheet edge against the outer sheet on the inner side of the outer sheet thus forming a joining groove, the fold and the inner sheet being joined by beam welding or beam brazing by welding or brazing head, and   wherein the inner sheet is held without clamping on an outer side of the inner sheet to the outer sheet which is fixed in a bed by hold-down devices, and is prevented from moving away from the outer sheet during a joining process by stops positioned on the outer side of the inner sheet.   
   
   
       2 . Method as claimed in  claim 1 , wherein during the joining process the inner sheet is held by releasable holders which are disposed in a row along the joining groove and in proximity thereto and hold the outer side of the inner sheet. 
   
   
       3 . Method as claimed in  claim 1 , wherein the stops clear a path for the welding or brazing head consecutively according to a progress of the joining procedure. 
   
   
       4 . Method as claimed in  claim 2 , wherein the releasable holders clear a path for the welding or brazing head consecutively according to a progress of the joining procedure. 
   
   
       5 . Method as claimed in any one of  claim 1 , wherein in a region of a joining section, the inner sheet is folded in a direction of the outer sheet. 
   
   
       6 . Method as claimed in any one of  claim 1 , wherein the inner sheet is supported on the outer sheet by a spacer element which is disposed between the outer sheet and the inner sheet in a region of a joining section. 
   
   
       7 . Method as claimed in  claim 6 , wherein the spacer element is a bead in the inner sheet or an insert body. 
   
   
       8 . Method as claimed in  claim 1 , wherein pressure is applied by the hold-down devices onto an edge of the fold of the outer sheet. 
   
   
       9 . Device for joining an outer sheet and an inner sheet of an attachment part, wherein
 holders are provided for the outer sheet and for the inner sheet, the inner sheet being held at a spaced interval above the outer sheet and with an inner sheet edge on an inner side in abutment against a folded edge of the outer sheet,   hold-down devices which press onto the folded edge of the outer sheet are provided on a side of the inner sheet remote from the outer sheet along a joining groove which is formed by the folded edge of the outer sheet and the inner sheet edge abutting against the folded edge,   stops are provided for the inner sheet edge,   a welding or brazing head is provided which can be displaced along the joining groove.   
   
   
       10 . Device in  claim 9 , wherein at least the stops are supported by pivotable blocks. 
   
   
       11 . Device in  claim 9 , wherein at least one hold-down device and at least one stop are each supported by a common block which according to a progress of a joining procedure can be adjusted from an operative position on the attachment part into a parked position which clears a movement path for the welding or brazing head. 
   
   
       12 . Device as claimed in  claim 9 , wherein a mechanical, pneumatic or electromagnetic holder which acts externally on the inner sheet can be activated in relation to holding function. 
   
   
       13 . Device as claimed in  claim 12 , wherein according to a progress of a joining procedure, the mechanical, pneumatic, or electromagnetic holder can be adjusted from its operative position on the inner sheet into a parked position which clears a movement path for the welding or brazing head. 
   
   
       14 . Device as claimed in  claim 13 , wherein each mechanical, pneumatic, or electromagnetic holder is supported by a pivotable, common block for one of the stops and one of the hold-down devices.